Refrigerating apparatus



Aug. 25, 1942. A, Q, GROWS 2,294,028

REFRIGERAT ING AP PARATUS Filed July 7, 1938 5 Sheets-Sheet 1 INVENTOR.

' ATTORNEYS Aug. 25, 1942. A. o. GROOMS REFRIGERATING APPARATUS Filed July '7, 1938 5 Sheets-Sheet 2 g z i INVENTOR.

2 ATTORNEY;

Aug. 25, 1942. A. R S 2,294,028

REFRIGERATING APPARATUS Filed July '7, 1938 5 Sheets-Sheet 3 Y ENTOR.

Aug. 25, 1942. A. o. GROOMS 2,294,028

REFRIGERAT I NG APPARATUS Filed July 7, 1958 5 Sheets-Sheet 4 f 0 gZVENTOR.

' provide a snap acting Patented Aug. 25, 1942 2,294,028 REFRIGERATING APPARATUS Albert 0. Grooms,

Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application July 7, 1938, Serial No. 217,928

19 Claims.

This invention relates to refrigerating and tempering apparatus and more particularly to control means for such apparatus.

In household refrigerators it has been customary to control the operation of the refrigerating system according to the temperature of the evaporating means in order that rapid ice freezing can be obtained. Such a the box temperature to fluctuate to a certain extent, with changes in environment temperature and also with evaporator temperature. Controls which have been governed by box temperature instead of evaporator temperature have been unsatisfactory because they did not provide sufficiently rapid ice. freezing. Various methods for compensating for different room temperature been found to be too for widespread use.-

It is an object of my invention to provide an improved simplified control for a household refrigerator which will regulate both the food comice freezing speeds.

It is another object of my invention to provide a control for a household refrigerating system which will maintain the box or food compartment temperature within very close limits and yet will provide rapid ice freezing.

It is still another object of my invention to provide a formof such control in which a very ing of the control and starting and stopping of the system can be obtained.

It is a more specific trol means.

It is still another object of my invention to switch means in which an electro-magnetic means is provided for moving the switch in one direction.

It is still a further object-of my invention to provide an improved adjusting means for a control means which regulates both food compartment and evaporator temperature.

My improved form of control is also applicable to heating and air conditioning systems. For example, the control system of control permits an anticipating effect when may be arranged so as to start the heating system when a predetermined low temperature is reached and to stop the heating system when a predetermined high temperature is reached instead of starting a refrigerating system when a predetermined high temperature is used and stopping the refrigerating system when a predetermined low temperature is reached.

In the simplest form of my invention the control takes the form of a bellows, thermostat bulb and connecting tube which is used to operate either the switch means or the valve for controlling a refrigerating system of the household type, or for controlling an air conditioning system wherein the bulb could be mounted upon some portion of the liquefying apparatus and used as a safety control, or for controlling a steam radiator in which the bulb could be mounted upon the radiator for an anticipating effect, or for controlling a furnace in whichthe bulb could be mounted in the stack, in a heating duct, or in mounted in the room. This form of control has th bulb is mounted vupon a heat exchange unit such as an evaporator radiator heats up faster than vthe surrounding air. The bulb which is tion with the heat transfer unit will have an frigerating system together with one form of control means for a household refrigerator embodying my invention;

Fig. 2 is a form of control means similar to Fig. 1 but arranged to maintain the evaporating means between extremely close temperature limits;

Fig. 3 is another diagrammatic illustration of a household refrigerating system showing an improved form of control basically similar to that shown in Fig. 1 embodying my invention;

Fig. 4 is another diagrammatic illustration of a refrigerating system showing another form of control applied to a refrigerating system in a mentioned bellows way so as to maintain the evaporating means between very close limits of temperature;

Fig. 5 is a structural embodiment of the con- 7 trol shown in Fig. elevation; I

Fig. 6 is a sectional view taken along the line H of Fig. 5;

Fig. 7 is a fragmentary view of a refrigerator the right;

Fig. 10 is a top sectional view of the pwitlon of the control shown in Fig. 8; and

Fig. 11 is a view showing the control mechanism in elevation and the non-metallic portion of the control housing in section.

Brief description Briefly, in Figs. 1 and 3 I have shown a refrigerating system with a form of control in which a bellows, bulb and connecting tubing are filled with a liquid refrigerant and the bellows is loaded so that the refrigerant will evaporate in the bellows when the food compartment temperature to which it is exposed reaches The bulb ismounted upon the evaporator and a second bellows is provided which is charged with vapor of the same refrigerant. The second bellows operates a switch mechanism and the first also operates a switch mechanlsm. The first bellows and switch is opened by the reduction in pressure within the bellows which is created by condensation of evaporated refrigerant within the bellows and by the liquid contraction of the liquid refrigerant in the bulb caused by .the fall in m means. This magnet which has its energization controlled by the second bellows and switch. The second bellows and switch is closed when the temperature and thereforepressure reaches a predetermined limit and is opened when energized under the control and switch. The control system shown in Figs. 2 and 4 are, in general, like those shown in Figs; 1 and 3 except that each bellows is provided with a bulb on the evaporator and both sets of the 4 and shows the control in.

a predetermined limit.

' the evaporating means reached a justment as wellas or loading spring.

Detailed description of Fig. 1

Referring now more particularly to Fig. 1 there is shown a refrigerating system including a compressor 20 driven by an electric motor 22 for compressing evaporated refrigerant and forwarding the compressed refrigerant to a condenser 24 where the compressed refrigerant is liquefied and collected in. a receiver 26. From the receiver 26 the liquid refrigerant is forwarded through a supply conduit 28 to a restrictor 30 which controls the flow of liquid refrigerant into the evaporating means 32, which preferably "has pro 'onsfor freezing ice cubes. This evaporating means 32 is located within the food compartment 34 of a domestic electric refrigerator cabinet which is indicated by the dot evaporating means 32 absorbs heat from the'air within the food compartment 34 as well as from any water in ice trays, and the refrigerant evaporates under reduced pressure-and is returned to the compressor 20 through the return conduit lieretofore, such a system has been controlled by a simple bellows operated thermostat switch connected in electrical series circuit relation with the electric motor 22 and controlled by mounting a thermostat bulb upon the evaporating means so that the refrigerating system-operated when predetermined high temperature and ceased operating when the evaporating means reached a predetermined low temperature of the evaporatswitch is-closed by an electro-f the electromagnet is I of the first bellows bellows and bulbs are provided with vapor charges rather than liquid charges.

In Figs. 7 to 11 a simplified form of the control The vapor charged bellows shown in Figs. 1 and 3 is omitted. In this simplified form the bellows, bulb and connecting tubing is provided with a complete or solid fill of liquid refrigerant, and the bellows is placed in a location in the food compartment so that it will be subject to food com partment temperatures while the bulb is placed in heat exchange relation with the evaporatin means. A switch mechanism is operated by the bellows and the customary loading spring or range spring is employed for loading the bellows sufficlently to control evaporation of the liquid refrlgerant in thebellows. 'A distance adjustment is provided between the bellows and the switch mechanism which it operates, and the selective temperature regulator operates this distance adtemperature. Such a, system was excellent for producing rapid ice freezing but did not provide any regulation of the box or food compartment temperature except that provided by the presence of the evaporator within the compartment. Unsuch a control was fairly der ordinary conditions satisfactory but when the room temperature was very low the food compartment temperature would belower than necessary while when the room temperature was high the food compartment temperature would be undesirably high. I

I, therefore, have provided a control which is responsive both'to evaporator temperature and to the food compartment temperature. This control includes a thermostat bulb 40 mounted upon and in, preponderant heat exchange relation with the evaporator and connected by tubing 42 to a bellows H which is mounted in the food compartment so as to be sensitive to the temperature of the food compartment, The bellows l4 operates a bellows follower connected by link 48. to a snap acting switch mechanism 50. The bellows It, th bulb ill-and the connecting tubing 42 are preferably completely filled fluoro-dichloro-ethane, in liquid at atmospheric pressure evaporate at temperatures slightly below the temperature which it is desired to maintain within the food compartment 34. v

The expansion of the bellows H is opposed by the range or loading spring 52 which is adjusted by the adjusting screw lapsing pressure is exerted upon the bellows 44 to prevent the evaporation of any of the liquid refrigerant in the bellows, bulb and connecting and dash outline 36. The

lever 46 which in turn is 54 so that sufficient col- 2,294,028 tubing as long as the temperature of the food- I refrigerant in the bellows 44 and this condensation will enable the spring 52 to open the snap acting switch mechanism 58.

The snap acting switch mechanism a contact bar 58 which is adapted to bridge the contacts 58, 68 and 62. The contact 58 is connected to the conductor 54 which connects to one of the supply conductors while contact 68 is connected to the conductor 56 which in turn is connected to one of the terminals of the compressor driving motor 22. Thus when the snap acting switch mechanism 58 is closed, the contact bar 56 will bridge the contacts 58, 60 and 62. This will cause the electric energy to flow from the 50 includes With such a system, if the food compartment temperature should becom sufliciently high, the liquid refrigerant would evaporate within the bellows 44 and cause the snap acting switch means 50 to close and start 'the operation of the motor compressor unit. This would lower the temperature of the evaporating means and cool the air within the food compartment. Thi coolcompartment would the bellows 44 and cause the evaporated refrigerant within the belto the laws of liquid expansion and would the bellows 44 to move the snap acting switch means 50 to closed circuit position. This would cause the refrigerating system to operate and cool the evaporating means and when the evaporating means reached a suficiently low temperature the spring 52 would cause the bellows follower lever 46 to be pulled downwardly because of the contraction of the liquid within the bulb 40 and the snap acting switch mechanism would again be moved to open position. Thus, with such a system the evaporator temperature would be regulated by the liquid expansion within the thermostat bulb 48 while the'food compartment temperature would be regulated by the evaporation of theliquid refrigerant in the bellows 44. v

The sensitivity of the snap acting switch 58 to the change in evaporator temperature depends upon the relative size of the thermostat bulb 40, the bellows 44 and connecting tubing 42 as well as the amount of multiplication provided by the bellows follower lever and the snap' action mechanism. The sensitivit of the switch mechanism to the food compartment temperature is regulated by the heat exchange relation of the belmature 88 44 to the air in the food compartment 34 as well as by the characteristics of the refrigerant and the adjusting spring 52, and also the characteristics of the bellows 44 and the snap acting mechanism 58.

I have found that under many conditions it is difiicult to obtain a sufliciently close regulation of food compartment temperatures by a simple system such as has been just described. In order to obtain a closer regulation of food compartment This belis provided with a vapor charge of the same refrigerant which-is provided in the bellows 44, connecting tubing 42 and the lower lever 12 which in turn is connected by a link 14 to a snap acting mechanism 16 which operates a contact bar 18 for bridging the contacts 88 and 82. The expansion of the second bellows 18 is controlled by a range or loading spring 84 which is adjusted by the adjusting screw 85 so that the bellows 18 will have sufficient vapor pressure to close the switch when the food compartment temperature reaches the desired high temperature limit.

The contact 82 is connected by the conductor 88 to the same terminal of the to the contact 82 of the snap acting switch 50. The electromagnet 82 is connected by the conductor to the conductor 84 which connects to one of the supply conductors. this arrangement the contacts 88 and 82 are 'connected in parallel electric upon the bellows follower 12 to cause the switch 16 to be opened thereby deenergizing the entire system.

is assumed'that each of the snap acting switch mechanisms have a differential which is compressor motor '22 to-the nism 50 to closed position.

. food compartment 34 f compartment and considerably greater than the limits 40 and 41 F. which have been assumed as the desired tem ential of F. it would not close until the food 1 compartment reached a temperature of 50 F. Since the refrigerating system has been deenergized. by the opening of both the switches 50 and 16 the temperature of the food compartment will begin to rise. When the temperature of the bellows 10 and the temperature of the food compartment 34 reaches 41 F. the switch mechanism 16 will be closed. This will permit the flow of current from the conductor 66 through the contact 82, the contact bridge 18, the contact 80, the conductor 90 and the electromagnet 92. the conductor 96 to the conductor 64, thereby energizing the electromagnet 92. The energization of the electromagnet' 92 will attract the armature I02 which is provided upon the end of the bellows follower 46 and will pull the snap acting switch mecha- This will cause the bridging of the contacts 58, 60 and 62 and will permit the current to by-pass the electromagnet 92 by flowing through the conductor 94 to the contact 62 and through contact bar 56 to the contact 58, and thence through the conductor 64 to the power source.

While 40 F. is set as the desired low temperature limit for a food compartment this tempera-- time will be varied by the influence of the thermostat bulb 40 which is mounted upon the evaporator 32. Thus approaches 40 F. and a warm ice tray isplaced within the evaporator 32the liquid expansion within the thermostat bulb 40 will prevent the opening of the' switch 50 so that the system will continue to operate even though the food compartment temperature has reached 40 F. However, since there is much better heat transfer between the air in the food the evaporator, the food compartment will not be cooled much below 40 F.

. even under such conditions.-

If the switches are open and warm ice trays are placed within the evaporating means the liquid expansion within the thermostat bulb 40 will expand the bellows 44 and cause the switch 60 to close thereby causing the operation of the refrigerating system even though the food compartment temperature has not reached 41 F.

The'control of the refrigerating system, according to evaporator temperature, is governed by the linear relationship of the bellows to the switch means, by t e, relative volume of the thermostat bulb with respect to the volume of the bellows and the connecting tubing and by the amount of liquid charge. Because the evaporator is used for freezing purposes, it is ordinarily necessary that the refrigerating system be started as well as stopped at temperatures below the freezing point of water. Therefore, the thermostat bulb 40 and the bellows 44 are filled with the liquid control refrigerant to such an extent that the switch means will close when the evaporating means is below freezing, and will open when the evaporating means reaches a temperature considerably below freezing. Thesetemperatures can be controlled by varying the ratio of the volume of the bellows if the temperature of theto the volume Detailed description of Fig. 2

The construction of the system shown in Fig. 2 is like that shown in Fig. 1' except that the upper or second bellows is provided with a thermostat bulb thermally connected to the evaporating means and both the bellows are provided with a vapor charge. With this system it is possible to maintain thetemperature of the evaporating means between exceptionally close limits such as 02 F. For example, the system may be such that the compressor evaporator temperature reaches 9.2 F. and to cease operation when the temperature reaches 9.0 F.

Like Fig. l the system includes a compressor I20 driven by an electric motor I22 for compressing evaporated refrigerant and forwarding the compressed refrigerant to the condenser I24 where the compressed refrigerant is liquefied and collected in the receiver I26. From the receiver, the liquid refrigerant is forwarded through the conduit I28 to an evaporating'means I32 under.

the control of a restrictor- I30. The evaporating means I32 is located within a compartment I34 having its wall indicated by the dot and dash outline I36. The evaporating means I32 evaporates the liquid refrigerant under reduced pressure and absorbs heat from the medium to be cooled within the compartment I34. The evaporated refrigerant is returned to the compressor through the return conduit I36.

' The evaporating means I32 has thermally connected to it a thermostat bulb I40 connected by tubing I42 to a bellows I44 which operates a bellows follower lever I46 which in turn is connectacting switch mechanism I50. The expansion of the bellows I44 is opposed by a tension coil spring I52 which has its tension regulated by the adjusting screw I54 so that switch mechanism I50 will be opened when the temperature of the evaporating means I32 and the thermostat bulb I40 reaches 9.0 F., when the bulb I40 is provided with a vapor charged a volatile liquid. A second bellows I10 is'operably connected toa bellows follower lever I12. The bellows I10 is connected by tubing I69 to a thermostat bulb I61 mounted in prepondering heat exchange relation with the evaporating means I32. The bulb I61 is preferably charged with a vapor charge of the same refrigerant as is provided in the bulb I40.

A tension type coil spring I84 opposes the expansion of the bellows I10 and has its tension adjusted by the adjusting screw I86 so that the switch contacts I16 which are operated by the lever I12 through the link I14 will be closed when the temperature of the evaporating means I32 and the thermostat bulb I61 reaches 9.2 F. The snap acting switch means I16 operates a contact her I18 for bridging the contacts I60 and I82. The contact I62 is connected by the of the bulb and by varying the amount of liquid charge of the refrigerant at operates when the contact I62 of conductor I88 to one of the compressor driving motor I22. .The other terminal of the compressor driv' g motor I22 is connected by a conductor I68 to one of the power supply conductors. The contact I80 is connected to conductor I80 which at its terminus is connected to one end of the electromagnet I92. The conductor I80 is also connected to a conductor I94 which is connected to the the snap acting switch mechasnap acting switch mechanism contact bar I56 which bridges the contacts I62, I60 and I58. The contact I58 is connected by the conductor I64 to one of the supply conductors while the contact I60 is connected by the conductor I66 to the conductor I88 which connects to one of the terminals of the compressor driving motor I22. The other end of the electromagnet I82 is connected by the conductor I86 to the conductor I64 which connects to one of the supply conductors.

As shown both switches are closed indicating that the compressor is operating and that the temperature of the evaporating means is above 9.0 F. and that the temperature of the evaporating means has previously reached 9.2 and in that way has caused the compressor to begin to operate. The current to the compressor driving motor passes through the conductor I63 to the electric motor I22, thence through the conductors I88 and I66 to the contact I60 through the contact bar I56 to the contact I58, thence through the conductor I64 to the other power supply conductor. When the temperature of the evaporating means I32 and the thermostat bulb I40 reaches 9.0 F. the tension spring" I52 will open the snap acting switch means I50. This will provide the flow of current through the conductor I88 to the contact 582 through the contact bar I18 to the contact I80, thence through the conductor I90 and through the electromagnet I92, the conductor I86 and the conductor I64 to the other power supply con- The flow of current through the electromagnet I92 will attract the armature I98 upon the bellows follower lever I12, thereby causing the opening of thesnap acting switch I16 to deenergize the compressor driving motor I22.

The stopping of the compressor driving motor will allow the evaporator I 32 to warm up and when the temperature 9.2" F. is reached, the snap acting switch means I16 will close, thus causing the current to flow through the compressor driving motor I22 and electromagnet I92 thereby attracting the armature 202 upon the free end of the bellows follower lever I46 to cause the closing of the snap acting switch mechanism I 50. The closing of the switch I50 will provide a shunt around the electromagnet I82 and cause the compressor driving motor to be normally energized. As explained in connection with Fig. 1 this system may be employed for controlling a heating device by rearranging the contacts so that they open upon the expanterminals of the nism I50. The I50 operates a sion of the bellows and close upon contraction of the bellows.

Detailed description of Fig. 3

In this form a somewhat different form of switch mechanism is provided but the function of the control is the same as that shown in Fig. 1. Inthis figure there is shown a compressor 220 for compressing the refrigerant and forwarding the compressed refrigerant to a condenser 224 where compressed refrigerant is liquefied and colexpansion of the lected in a receiver 226. From the receiver 226 the liquid refrigerant is forwarded through a sup ply conduit 228 to a restrictor 230 which controls the flow of liquid refrigerant into the evaporating means 232 which is located within the compartment 234 containing a medium to be cooled. The compartment is enclosed by a casing indicated by the dot and dash outline 236. The compressor 220 is driven by a driving motor 222.

A thermostat bulb 240 is thermally connected to and in prepondering heat exchange relation with the wall of the evaporating means 232 and is connected by tubing 242 to a bellows 244. The bulb 240, the tubing 242 and the bellows 244 are preferably filled with a solid charge of a volatile refrigerant in liquid form. This refrigerant preferably has an atmospheric boiling point slightly below the temperature at which it is desired to keep the medium to be cooled within the compartment 234. For example, in an ordinary refrigerator it is desirable to use tetrafluorodi- 'chloroethane which boils at about 38 F. However, other refrigerants having boiling points close to 38 F. or even somewhat lower'than 38 may be used for this type of application. The bellows 244 operates a bellows follower switch lever 246 which is provided with a contact bar 256 at its free end. In order to provide a snap action for controlling the opening movement of the contact bar 258, a permanent magnet 248 is provided which exerts an attraction upon the bellows follower lever 246.

The expansion of the bellows 244 is opposed by the tension coil spring 252 which is provided with an adjusting screw 254, so that its tension may be regulated to cause the opening movement of the contact bar 256 when the temperature of the medium to be cooled in e compartment 234 reaches the desired low temperature limit, such as 40 F. The contact bar 256 is adapted to make engagement with the contacts 258, 260 and 262. The contact 260 is connected to the conductor 264 which in turn connects to a conductor 263 connected to one of the supply conductors. The contact 258 is connected by a conductor 258 to a conductor 266 having one end connected to the electromagnet 282 and the other end connected to the compressor driving motor 222 which in turn is connected by a conductor 268 .to the other power supply conductor. The other end of the electromagnet 292 is connected by a conductor 296 to a conductor 290 which is connected to a contact 280 of the second switch mechanism. The contact 262 is also connected by a conductor 294 to the conductor 290.

The conductor 263 is connected to the second contact 282 of the second switch mechanism which has a contact bar 218 bridging the contacts 280 and 282. This'contact bar 218 of the second switch mechanism is operated by a bellows 210 containing a vapor charge of the refrigerant with which the bellows 244 is charged. However, if desired a different vapor may be used. The bellows 210 operates a bellows follower lever 212 which in turn operates a double toggle snap acting switch mechanism 216 which opcrates the contact lever 214. The differential of this switch mechanism is controlled by the adjusting screw 215 which limits the opening movement of the contact lever 214 to control the differential of the double toggle mechanism. The

bellows 212 i opposed by a .tension type coil spring 284 which is adjusted by an adjusting screw 286 to such a tension that the bellows 210 will close the switch mechanism when 1 contacts 288 and 282 'bar 218, electric energy the contact bar 218 252 does not affect the control by the desired upper temperature limit of the medium to be cooled in the compartment 234 has been reached.

For example, the screw 236 may be adjusted so that the contact bar 218 will close the switch contacts at a temperature of 452 F. When the are closed will flow through the concontact 282, thence through to the contact 289, thence through the'conductors 296 and 296 to the electromagnet 292 and after passing through the electromagnet 292 the current will flow through the conductor 266 to one of the terminals of the compressor driving motor and through the compressor driving motor to the other terminal after which the current will flow through the conductor 268 to the other supply conductor.

The current flowing through the electromagnet will cause the electromagnet to attract the bellows follower lever 246 to cause the bridging of the contacts 258, 260 and 262 by the contact bar 256. This will permitthe current then to flow through the conductors 263 and 264 to the conductor 263 to the tact 269, thence through the contact bar 256 to the contact 258, thence through the conductors 258 and 266 to the compressor driving motor 222 and thence through thecompressor driving motor 222 and the conductor 268. Thus the electromagnet 292 is deenergized very quickly after the closing of the contacts 286 and 282.

The closing of the contacts will cause the operation of the refrigerating system and thereby reduce the tempera e of the medium to be cooled within the compartment 234. When the temperature of the medium to be cooled within the compartment is reduced to the predetermined low temperature limit for which the solid filled switch mechanism is set, such as 45 F., the contact bar 256 will be moved to open position, providing the evaporating means is below a certain temperature, thereby causing the motor current to flow through the electromagnet 292 thereby attracting the lever 212 and causing the double toggle switch mechanism to be moved to open circuit position. This will stop the operation of the refrigerating system.

The solid fill provided in the thermostat bulb 248, tube 242 and the bellows 244 also causes the switch mechanism to be operated according to the temperature of the evaporating means 232'. This operation, however, will take place under the laws of liquid expansion of the refrigerant,

by the contact whereas the control according to the temperature of the medium to be cooled in the compartment 234, will be according to the evaporation of the refrigerant in the bellows 244 and 216.

The loading of the bellows 244 by the spring liquid expansion, but only affects the control by evaporation in the bellows 244. The control by evaporator temperature through the liquid expansion depends upon a relative volume betwen the bulb 240 and the bellows 244 as well as the linear relationship between the bellows v244, lever 246 and the contacts 258, 260 and 262. By reversing the contacts so that they open with the expansion of all the bellows, this control may be used for controlling different forms of heating systems.

In Fig. 4 there is shown another form of control for a refrigerating system somewhat similar to that shown in Fig. 2. In this form two bellows and two bulbs, each in prepondering heat exchange relation with the evaporator, each with a vapor charge, are employed to obtain a close 328 under the control of a restrictor 336 to an evaporator 332 lodged within the compartment 334 enclosed by an insulated wall indicated by thedot and dash lines 336. The refrigerant evaporates within the evaporating means 332 under reduced pressure and absorbs heat from a medium to be cooled within the compartment 334. This evaporatedrefrigerant is returned to the compressor through the conduit 338.

A thermostat bulb 346 is mounted in prepondering heat exchange relationship with the evaporating means 332 and is connected by tubing 342 to the bellows 344. The second thermostat bulb 361 is connected by tubing 369 to a bellows 310. Each of these bellows, their bulbs and con-= nectlng tubing, are filled with a vapor of a volatile refrigerant. The bellows 344 operates a bellows follower lever 346 carrying a movable contact 356 which is adapted to make contact with a stationary contact 358 located-between the poles of a permanent magnet 348. The expansion of the bellows 344 is opposed by a tension type coil spring 352 which is adjusted by an adjusting screw 354 to cause the contact 356 to be pulled away from the contact 358 when the evaporator temperature is reduced to a predetermined low temperature such as 9.0 F.

The bellows 310 operates a bellows follower lever 312 which in turn operates a double toggle type of snap acting mechanism 316 which connects to the contact lever 314 carrying the contact'bar 318. The expansion of the bellows 316 is opposed by the tension type coil spring 384 which has its tension adjusted by an adjusting screw 386 so as to cause the contact bar 318 to be moved to open position when the evaporator reaches a predetermined high temperature such as 92 F. The contact bar 318 is adapted to bridge the stationary contacts 388 and 382. The

nected to the conductor 390 which in turn connects through the conductor 359 to the stationary contact 358 and which also connects to one end of the electromagnet 392, which is capable of attracting the bellows follower levers 346 and 312. The other end of the electromagnet 392 is connected by the conductor 365 to the bellows follower lever 346 and this bellows \follower lever 346 is connected by the conductor 366 to one terminal of the electric motor 322 while the other terminal of the electric motor 322 is connected by the conductor 368 to the other supply conductor. The contact 356'is electrically connected to the conductors 365 and 366 through the bellows follower lever 346.

The control mechanism in Fig. 4 is shown in a conditions the refrigerating system is idle and when the temperature of the evaporating means rises to the predetermined high limit, such as 9.2" F., the bellows 316 will expand and through the double toggle mechanism will move the contact bar 218 into closed circuit position. This will cause the" electric energy to fiow through the contact 3821s connected to the supply conductor by a conductor 363 while the contact 380 is conconductor 383 to the contact 382 and through the contact bar 318 to the contact 388, thence through the conductors 388 and 358 to the contact 358, thence to contact 358 and through a portion of the lever 348 to the conductor 388 which connects to the electric motor 322, and which is connected to the other supply conductor by the conductor 388.

Prior to the bridging of the contacts 380 and i 382 the bellows follower lever 348 is held in its uppermost position by a link 388 which connects the contact lever 314 with t'he'bellows follower 348 for holding the contacts 358 and 358 closed whenever the contact lever 314 is in open circuit position. This link 388 is necessary because the contacts 358 and 358 would not otherwise be closed by the bellows 344 until a temperature considerably above 9.2" F. was reached. Even though the contact lever 314 is moved to closed circuit position, the contacts 358 and 358 remain closed because the temperature of the evaporat ing means is still above its predetermined low limit. Thus at this time the contacts 358 and 358 are held closed without the support of the link 388.

However, when the predetermined low temperature limit is reached by the evaporating means by the operation of the refrigerating systern, the spring 352 will pull the lever 348 downwardly to separate the contacts 358 and 358. This will make it necessary that the electric current flowing through the electric motor 322 pass through and energize electromagnet 382 and thence through the conductor 385 to the conductor 388 in order to attract the bellows follower lever 312 and move the contact lever 314' to'open circuit position. By reversing the operation of the contacts this control system may also be used for controlling a heating system.

Detailed description of Figs. and 6 Figs. 5 and 6 show a structuralembodiment of the control means shown in Fig. 4. In this form there is shown a box-shaped casing member 482 of a molded insulating material, on the left side of which is fastened a metal frame 484. This metal frame 484 supports a bellows 418 which corresponds to the bellows 318 in Fig. 4 and is provided with tubing 488 which may be connected to a thermostat bulb mounted upon an evaporator. The bellows 418 operates a bellows follower lever 412 which is pivoted to the tongue 488 extending from the metal frame 484. The other end of the bellows follower lever 412 is provided with notches which receive the chiselshaped ends of the secondary lever 488 which in turn is connected at its opposite end to a tension coil spring 418 having its other end connected to an upwardly extending portion of the contact lever 414. The bellows followerlever 412 has a downwardly extending portion 2 to which is fastened the upper end of a tension coil spring 484 having its lower end connected to a walking beam type lever 485 pivoted at its midpoint and connected at its other end to a threaded member 481 which receives the lower end of the-adjusting screw 488.

The contact lever 414 ment controlled by the 415 and at its lower end is provided with a contact bar 418 which is adapted to bridge a set of contacts 488. One of these contacts is connected by the conductor 488 to the electromaghas its opening moveadjustable stop screw net 482 which is mounted within the insulatedlever 448 to the frame 484.

HI capable of attracting at its upper end the bellows follower lever 412 and at its lower end a second bellows follower lever 448. This same contact is also connected through a conductor and screw 458 to a bracket which supports the stationary contact 458'which is adapted to be contacted by a movable contact 458 mounted upon a leaf spring connected through the contact lever 448. A horseshoe-shaped permanent magnet 448 is fastened to the outside of the box 482 so that it will attract the bellows follower lever 448 to provide a form of snap action The bellows follower lever 448 is provided with upwardly extending ears through which a pivot pin 4| 8 extends and which pivotally connects the The frame 484 has a downwardly'extending portion 8 which supports the second bellows 444, which may be connected to tubing 442. The upper end of this bellows is provided with a conical point which is used to operate the lever 448. The expansion of the bellows 444 is opposed by acompression type coil spring 452.

This control may be used with both bellows filled with a vapor charge and each connected to a thermostat bulb, or the bellows may be used without thermostat bulbs and with a vapor charge and, under such conditions, would be responsive to the temperature of the air with which they might be in contact. If desired the. bulb 418 may be used with a-vapor charge without any bulb connected to it, while the bellows 444 box 482 as shown, and is provided with a core may be connected to a bulb mounted upon an evaporator andprovided with a solid charge; that is a solid fill of a volatile liquid refrigerant.

Detailed description of Eigs. 7 to 11 practical commercial form of a control heretofore described in connection with Figs. 1 to 6 and it particularly resembles that portion of the control shown in Fig. 1 which includes the bellows 44 and a switch mechanism operated thereby, together with its thermostat bulb and connecting tubing filled with a solid liquid charge of a volatile refrigerant. While it is more diflicult to obtain a close regulation of food compartment temperatures with this single bellows form of control, in many cases by particular precautions it is possible to so design this form to achieve satisfactory regulation of box temperatures and evaporator temperatures within the household refrigerator.

Fig. 7 shows a household refrigerator includ ing an insulated cabinet 5| 8 containing a food compartment 5| 2 made accessible by a food compartment door 514. Within the food compartment 5l2 is a sheet metal evaporator 532 provided with a lower shelf. and an upper shelf for supporting ice trays which may be provided with water or other substances to be frozen. This evaporating means 532 .is supplied with liquid refrigerant by a compressor 528 which com-- The liquid refrigerant evaporates I ciflc location shown in Fig.

filled completely with a liquid tending into the interior of cabinet has a relatively high within the evaporating means 532 under reduced pressure and absorbs heat from the air within the food compartment l2 as well as from any ice trays which rest upon the shelves of the evaporator.

In order to control both the temperature of the air within the food compartment and the evaporator temperature I provide a simplified form of control such as is shown in Figs. 1 and 3, which omits the vapor charged bellows and its switch means and relies wholly upon a single solid liquid charge of volatile refrigerant in the bellows, bulb and connecting tube. This control includes a'switch casing 5|6 mounted upon the bottom face of top wall of the food compartment so that it is in the path of the air which circulates within the food compartment. The natural circulation within the food compartment is normally upwardly along the walls to the top of the cabinet and thence downwardly along the outer wallsof the evaporating means to the central portion of the food compartment. The switch casing 516 need not be placed in the spe- 7 but may be placed anywhere within the food compartment where it will be responsive to the temperature of the air in the food compartment.

The switch casing 5l6 H refrigerating load require lows proportionately should be smaller and the thermostat bulb should be proportionately larger. That is, where there is a relatively high difierence in temperature between the evaporator temperature and the food compartment temperature,

a relatively smaller bellows in proportion to the volume of the bulb should be used. I find that refrigerators which are well insulated and the refrigerating system is well proportioned to the that the ratio of the volume of the bulb to the volume of the bellows should be between about two to one and one to one. For example, the volume of the bulb to the .volume of the bellows might be in proportion of six to five.

The well 608 slidably receives a thimble 6"] which has a reduced upper portion providing a flange which normally rests against an angular retainer 6l2 fastened to and sealed to the top of 30 the bellows. The flange of the thimble 6H1 is contains a bellows 544 which is mounted upon the switch frame 602 and fastened thereto by a thin nut 604 which threads onto a threaded fitting downwardly from the base of the bellows 544 through an aperture in the frame 602. Extending from the threaded fitting 666 is a small bore capillary tube 542 which at its upper end connects with the interior of the bellows 544 and which at its other end connects to a thermostat bulb 545 which is mounted upon the inside wall of the evaporating means 532 directly underneath the upper ice tray shelf. If is, however, not necessary that this speciflc location of the bulb be used since any location which reflects the temperature of the evaporating means will prove satisfactory. It however, necessary that the bulb 545 be in prepondering heat exchange relationship with the evaporator while the bellows 544 must be in prepondering heat exchange relation with the medium which is cooled by the evaporator.

Inasmuch as the bellows, bulb and tube are refrigerant it is necessary to provide a means for accommodating the liquid expansion of the refrigerant under high temperature conditions, such as are encountered when the refrigerator is being h pp d. For example, should the refrigerator be shipped or stored under conditions which would subject it to a temperature of 140 F. some means must be provided to accommodate for the liquid expansion of the refrigerant under such conditions. In order to do this I have provided a well 608 exthe bellows and having its upper edges provided with a flange to which the upper end of the bellows is sealed.

This well 688 not only-serves to retain the means for accommodating the liquid expansion of the refrigerant under unusual conditions but also serves to reduce the volume of the bellows 544 so that the volume of the bellows may be kept in a desired proportion to the volume of the thermostat bulb 545. The desirable proportions of the volume of the bellows to the volumeof the bulb depend upon the refrigerating system and its cabinet. Where the heat leak the bel 606 extending by a thin lock lever 626 normally held against the angular retainer 6 I2 by a compression type coil spring 614 which may be overcome when the liquid expansion of the refrigerant within the bellows and bulb becomes great. The upper end of the thimble 6! is provided with a conically pointed projection 6l6 which engages the recess in the bottom of the adjusting screw 6! which is threaded through the bellows follower lever 620 and locked in place nut 622.-

This bellows switch frame 602, as'has been customary in the past, butwhich instead is mounted upon a second which is pivotally connected to an.upwardly extending portion 628 of the switch frame 602 by a spring hinge 630 which is formed of spring bronze and which is riveted to the portion .628 and to the lever 626,so that it serves to retain 40 the pivot'pin 624 as is shown in Figs. 8 and. 10.

The bellows other side of the switch box and is provided with a downwardly extending portion 632 provided with a notch which receives the chisel-shaped ends. of a secondary lever 634 having its free end lever 636 vided with an upwardly extending post 640 which received within of the contact carrying oted upon the pin 63.8 to the frame member 662.

at the portion opposite its pivot is prothe notches provided in the end lever 636 which is pivthe rear wall portion of supports one end of the tension type coil spring 642 having its other end connected to the free end of the secondary lever 634. The secondary lever 634 and the tension coil spring 642 together provide a double toggle type snap action mechanism for controlling the opening and closing movement of the contact carrying lever 640.

The contact carrying lever 640 is provided with an arm 644 which contacts the turned down end of a leaf spring 646 whichserves as a stop to limit the normal opening movement of the contact carrying lever 640. It should be understood that the amount of movement of the cont-act carrying lever between open and closed position determines the difierential of the double toggle contact mechanism. The leaf spring 646 is fastened at its opposite end to the top portion 648 of the frame member 602 by a screw 65!]. This 7 leaf spring member 646 is provided with an apercharacteristics' of the splined connection is connected to the adjusting follower lever 620 is pivoted upon a pin 624 which is not rigidly mounted to the follower lever 620 extends to the The contact carrying position and the leaf spring clockwise stationary contact is mounted driving motor 522.

screw 654. The bottom of this collar is provided with a cam which 658 which also extends from the contact lever 636 for the purpose of forcibly holding the contact lever 638 in open circuit position to stop refrigeration. The collar is turned by the knob 656 for this purpose to the proper position.

The knob may also be pushed inwardly to depress the leaf spring 646 sufiiciently so that the arm 644 will ride over the top of the leaf spring 646 and permit a greater opening movement of the contact lever 640. This greater opening movement ofthe contact lever 64!! will be limited by a stop screw 660 which extends downwardly through the car 662 provided in a portion of the switch frame 602. This screw is adjustable and may be locked in place by the locking screw 664. This wider differential raises the temperature at which the switch mechanism will be closed and the adjusting screw 660 is preferably so set that by this manipulation the evaporator must reach a temperature above freezing before the switch can be closed so that the evaporator will defrost. When the evaporator reaches a sufliciently high temperature the bellows will move the contact lever 636 to closed 646 will return to its normal position as shown in Fig. 11 by its own resiliency and the difierential will thereby be returned to normal. The temperature of the food compartment which must be reached before it can cause the switch to close is also raised forthis defrosting operation.

The contact lever 636 operates a set of switch contacts, the upper of which is mounted upon the spring member 565. This spring member 686 by its resiliency holds the upper contact away from the lower contact whenever the contact lever 636 is moved upwardly or in a counterdirection about its pivot pin 638. The

tion 668 of insulating material The adjusting screw 554 carries an irregularly shaped strip metal member 610 which is threaded thereon but which is prevented from rotation by tongues which extend into a vertical groove provided in the rear wall of the switch frame 602.

This member 610 has a lower portion 612 to which is connected the lower end of a tension type coil spring 614 having its upper end connected to the bellows follower lever 620 and serves to properly load the bellows 544. The member 610 has an upwardly extending portion 616 provided with a notch 618 which receives the free or lower end of the hinge lever 625 which supports the pivot pin 624. Thus by the turning of the control knob 658, the loading; of the bellows 544 is controlled and also the location of the pivot pin 624 is controlled simultaand at the same time vary the loading of the bellows through its -loading spring 614 so that the temperature of the evaporating means and the food compartment temperature may be siis adapted to engage the arm by the bottom layed until the be varied by providing different leverage for the pivot pin lever 626 and by providing a difierent rate spring for the loading spring 614.

The switch casing 5E6 encloses the switch mechanism except for the bottom which is closed portion of the switch frame. I have found that it is not necessary to provide perforations in the switch casing 5| 6 since it appears that suflicient thermal conductivity is ordinarily obtained through the switch frame to provide a suificient heat transfer between the air in the cabinet and the bellows to cause the vapor pressure within the bellows 544 to correspond to the temperature of the circulating air within the food compartment.

In operation, when the evaporator reaches a predetermined high temperature limit the liquid refrigerant within the bulb 545 will expand sufficiently according to the laws of liquid expansion to expand the bellows 544 sufficiently to move the switch mechanism to closed circuit position. When theevaporator reaches its low temperature limit the liquid within the bellows 544 will contract sufl'iciently to permit the switch mechanism to be moved to open position under the force provided by the loadingspring 874. However, if the evapora or should be at its low temperature limit and the air within the food compartment is' still above the desired temperaprevent the switch from opening until the temperature of the air within the food compartment has .become .low enough to allow the loading spring 614 to collapse the bellows 544 by condensing substantially all of the vapor in the bellows.

If the evaporator temperature is between its normal temperature limits and the air within the food compartment should become too warm, because of opening the food compartment door, or placing a large amount of warm food into the refrigerator, the refrigerant within the bellows will vaporize and move the switch to closed position and start the operation of the refrigerating system so that refrigeration need not be deevaporator has reached its high temperature limit. This arrangement also compensates for varying room temperatures since under hot room conditions the vaporization of the refrigerant-within the bellows will prevent the stopping of 'the refrigerating system until the food compartment temperature is below its high temperature limit, conditions the cold air within the food compartment will contract the liquid within the bellows sufiiciently to prevent excessively cold temperatures within the food compartment.

Under extreme temperatures when the system is not in operation the be lows may expand until the bellows follower lever stops against the switch frame. after which the bellows may further expand because further expansion will be accommodated by the thimble Bill which will be pressed further into the well 608 against the tension of the spring 6M and away from the flange BIZ. In normal operation, however, the thimble 610 will always remain in the position shown in Fig. 8, with its flange against the angular stop ring 6l2 so that the linear relationship under normal operation will always remain thesame.

In order to stimulate evaporation of the volatile liquid within the bellows to preserv the and under cold room pressure-temperature relationship of the volatile liquid, insoluble crystals or sharp metal projections may be provided in the bellows. This prevents any superheated liquid condition which has the effect of elevating the boiling point of the volatile liquid. This superheated liquid condition is more serious when there is considerable pressure upon the liquid in the bellows, as is necessary when the boiling point of the volatile liquid is considerably below the temperature at which it is desired t maintain the medium to be cooled.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope I of the claims which follow.

What is claimed is as follows:

1..Refrigerating apparatus including a means to be cooled, a cooling unit for cooling said means,. and a refrigerating supply means for supplying refrigerating fluid to said cooling unit, a control means for controlling the supply of refrigerating fluid to said cooling unit, said control means including an actuating means containing a volatile liquid, said actuating means including a portion in heat exchange relation with said cooling unit, said actuating means bein substantially filled with said volatile liquid in its lquid phase, said actuating means having a secend portion containing a free liquid surface of said volatile liquid where the volatile liquid can vaporize and where the vapors can collect, said second portion being located in heat exchange relationship with said means to be cooled.

. 2. Refrigerating apparatus including a means to be cooled, a cooling unit for cooling said means, and a refrigera ing supply means for supplying refrigerating fluid to said cooling unit, a control means for controlling the supply of refrigerating fiuid to said cooling unit, said control means including an actuating means containing a volatile liquid, said actuating means including a portion in heat exchange relation with said cooling unit, said actuating meansbeing substantially filled with said volatile liquid in its liquid phase, said actuating means having a second portion containing a free liquid surface of said volatile liquid where the volatile liquid can vaporize and where the vapors can collect, said second portion being located in heat exchange relationship viith said means to be cooled, and means for loading said actuating means sufficiently to cause said control means to be operated by liquid expansion and contraction when the temperature of the means to be cooled is below a certain limit and by evaporation within the actuating means when said temperature is above a certain limit.-

3. Refrigerating apparatus including a compartment containing a medium to be cooled, a cooling unit for cooling said medium, a refrigerating supply means for supplying refrigerating fluid to said cooling unit, a control means for controlling the supply of refrigerating fluid to said cooling unit, said control means including an actuating means having two portions in communication, the first portion being in prepondering heat exchange relation with the cooling unit, the second portion being in prepondering heat exchange relation with the medium to be cooled, said actuating means being substantially filled with a volatile liquid in liquid form, said second portion having a free liquid surface where the liquid can vaporize, means for applying sufilcient force to said volatile liquid to cause the vaporized volatile liquid to condense when the medium to be cooled reaches a predetermined low temperature and to evaporate slightly when the medium to be cooled reaches a predetermined high temperature.

4. Refrigerating apparatus including a compartment containing a medium to be cooled, a cooling unit for cooling said medium, a refrigerating supply means for supplying refrigerating fluid to said cooling unit, a control means for controlling the supply of refrigerating fiuid to said cooling unit, said control means including an actuating means having two portions in communication, the first portion being in prepondering heat exchange relation with the cooling unit, the second portion beingin prepondering heat exchange relation with the medium to be cooled, said actuating means being substantially filled with a volatile liquid in liquid form, said second portion having a free liquid surface where the liquid can vaporize, rue-ans for applying sufllcient force to said volatile liquid to cause the vaporized volatile liquid to condense when the medium to be cooled reaches a predetermined low temperature and to evaporate slightly when the medium to be cooled reached a predetermined high temperature,'said actuating means being also operable by liquid expansion and contraction of the volatile liquid.

5. Tampering apparatus including a medium to be tempered, a heat exchange unit in heat exchange relation with the medium to be tempered, means for supplying heat transfer fluid to said unit, means for controlling the supply of heat transfer fluid, said control means including an actuating means having two portions in' communication, one of said portions bein in prepondering heat exchange relation with the heat exchange unit, the second portion being in prepondering heat exchange relation with the medium to be tempered, said actuating means being substantially filled with volatile liquid in liquid form, one of said portions having a free liquid surface where the liquid can vaporize, and means for maintaining the pressure within said actuating means at a value sufficient to permit operation of the control means by liquid expansion and by evaporation of the volatile liquid according to predetermined temperatures of the unit and the medium.

6. A control means including ameans to be opened and closed, a plurality of separately movable operating means for said means to be opened and closed, said separately movable operating means each having different operating ranges between different predetermined limits, 2. first of said operating means being provided with means for closing said means to be opened and closed when a predetermined limit of its movement is reached, a second of said operating means being provided with means for opening said means to be opened and closed when a second predetermined limit of its movement has been reached, one of said operating means having its operating range above its predetermined limit and the other having its operating range below its predetermined limit, the portions ofthe operating ranges of said operating means adjacent said predetermined limits overlapping.

7. A control means including a means to be opened and closed, a plurality of separately movable operating means for said means to be opened and closed, each of said movable operating means having a different predetermined operating range of movement with relation to a control medium, said operating means including means effective ential, said difl'erent ranges overlapping.

8. A control means including a means to beoperated into either of two limiting positions, a

9. A control means including a snap acting device biased crating the means to be actuated.

12. A control means including an actuating means having a container portion, said container flexible wall means, a means the spacing between said follower member and said flexible wall means.

13. A con trol means including an actuating means having a containing portion substantially filled with cause all the dense when the portion containing the free liquid surface reaches a predetermined low temperature limit but insufilcient to prevent some of the volatile liquid from evaporating when the portion containing the free liquid surface reaches a predetermined high temperature limit for operating the means to be actuated.

14. A control operable in accordance with both the liquid expansion and evaporation of a volatile liquid comprising an actuating means having a containing portion provided with a portion free liquid surface where evaporated volatile liquid may collect and condense, said entire containing portion being substantially enliquid in its liquid predetermined to prevent the evaporation of volatile liquid when the portion containing the free liquid surface rises above said predetermined temperature limit.

15. A control operable in accordance with both the liquid expansion and evaporation of a volatile liquid comprising an actuating means having a containing portion provided ing a free liquid surface where evaporated volawith liquid when the portion containing the free liquid surface goes below a predetermined temperature limit but insuiiicient to prevent the evaporation of volatile liquid when with a portion hav-' perature of the diaphragm -means is above a certain limit.

17. A control including a diaphragm means, a

snap acting means operated by the diaphragm means, a. spring means for loading the diaphragm means, an adjustable operating connection providing a spacing between the diaphragm means and the snap-acting means, and manually operable means for simultaneously adjusting the tension of said spring means and the adjustable operating connection to adjust the spacing between the diaphragm means and the snap acting means.

18. Refrigerating apparatus including a means to be cooled, a cooling unit for cooling said means, and a refrigerating supply means forsupplying refrigerating fiuid to-said cooling unit, a control means for controlling the supply of refrigerating fluid to said cooling unit, said control means including a diaphragm operating means containing a diaphragm chamber in preponderant heat exchange relationship with said means to be cooled, said control means also including a thermostat bulb containing a chamber in preponderant heat exchange relationship with said cooling unit, tubing connecting said chambers, said diaphragm and bulb chambers and said tubing being substantially filled with a volatile liquid in its liquid form, and means for loading said diaphragm means sufiiciently to condense ali vapor-of said volatile liquid when said diaphragm means is below a certain temperature limit but insufficiently to prevent evaporation when said diaphragm means is above said temperature limit to cause said control to operate according to liquid expansion and contraction under the influence of the cooling unit and according to vapor pressure under the influence of the means to be cooled.

19. A control including a plurality of actuating means, electromagnetic means operating to move one of said actuating means, and switch means' controlled by said one and another of the actuating means for controlling the energization of I the electromagnetic means.

ALBERT 0. GROOMS. 

